The proposed research has two principal components: first, an evaluation of the usefulness and costs of selected diagnostic tests and technologies performed in the clinical laboratory; and second, a description of the process by which new laboratory equipment is put into use and an analysis of the desirability and opportunities to intervene in that diffusion process. The specific studies will concern automated multichannel chemistry analyzers, white blood cell differential counters and certain individual laboratory tests. The methods used in this research include investigation of the diffusion of automated laboratory equipment by means of literature revies, market surveys, interviews and questionnaires. Economic and cost-effectiveness analyses will be conducted on both the chemistry autoanalyzer and white blood cell differential counters. Individual chemistry tests will be evaluated in terms of an expanded cost-effectiveness framework described in the proposal and these results will be incorporated into the assessment of the net cost and clinical value of automated chemistry equipment. The proposed investigations of laboratory tests and technologies fit into a broader assessment of diagnostic technology that includes also imaging and physiologic function tests. Diagnostic technologies as a class raise particular methodologic issues in the evaluation of efficacy, cost and cost-effectiveness. Our aim is both to perform the analyses in the specific areas described and to establish analytic models applicable as well to other diagnostic tests and technologies.